What is causing this reflection on a surface? (Blender Guru coffee cup tutorial)
I think I managed to fix it. After experimenting with the scale of the liquid and HDRI and shading settings, I found out it was neither of these.
I hid the liquid by using the eye icon while in render view and I noticed the line was still there, and when I switched to object view, it still looked like there was a still a liquid shape. What I think I did was duplicate the vertices and right clicked rather than make a separate object. I then created a new liquid layer on top.
So what I did was click on the cup in Edit Mode and then Merge Vertices &gt; By Distance. This effectively removed that additional liquid layer I had in the cup object.